Telephone-exchange system



June 1 1926. 1,586,538

G. THOMPSON TELEPHONE EXCHANGE SYSTEM Filed Nov. 3. 1923 'I I I hu a/22b? George Thom/son.

' June 1 1926. 1,586,538

G. THOMPSON TELEPHONE EXCHANGE SYSTEM File v. 5, 1923 7 Sheets-Sheet 2 "3 u u? SQ Gear 6 7720/77 50.

June 1 1926. 1,586,538

G. THOMPSON I TELEPHONE EXCHANGE SYSTEM Filed Nov. 5. 1923 '7 Sheets-Sheet 5 Q as g hven/b/ Geagye Thompson.

June 1 1926.

G. THOMPSON TELEPHONE EXCHANGE SYSTEM Filed Nov. 3. 1925 v Sheets-Sheet 4 QB w 82 hven/or: Geo/ye Thom $012 Alf ' June 1 1926.

G. THOMPSON TELEPHONE axcnmca svs'mu '7 Sheets-Sheet 5 Filed Nov. 5i 1923 mm faw m w w I. o- LI 0M n e can a //7V/ 7/0/: Geo/ye Thom say,

June 1 ,19 26. 1,586,538

' G. THOMPSON TELEPHONE EXCHANGE SYSTEM hvenfon- George, Thompson.

, v b r 1417 June-1,1926. 1,586,538'

G. THOMPSON TELEPHONE EXCHANGE SYSTEM Filed Nov. 3. 1923 '7 Sheets-Sheet v T kink m c Commumrors QM Disrricr Frame T 'T-W Subscribers and Operators Subscribers Dimncf senders //7ve/7f0k."

Geo/ye Thom 0500 y T?unksTo other Offkes GEORGETHOMPSONQ or iirountr' vnrgnon, NEwYoRK, Assrenon'ro wrisTERnJn'L'nc-f ygemrnoliam mm mum.

jhpplicatioii filed November 3, 923} Serial 1%. 672, 56? it i i invention to automatic telephone exchange systems and more particu larly to exchange systems in which operators v are. equipped witlilcallingwdials; T v

available for use, both bycalling subscribers and by operators,- which will" discriminate either class of incominglines. 5 T

By the use" of this; invention a l' more economical grouping of 'selectors may be efi fected since it will no longer be necessary 1 toflprovide'separate groups ofdistricts'and o I g 11in order to coordinatethem properly;

associatedfgroups; of senders to serve subscribers'and separate groups to serve operatorsJ-f, l f

A feature of this invention 1s the pro-.

. between an-operators call and a subscribers IA further feature resides in themethod of ordinarily controlled bythe' office cod'e dialled and substituting (an-other selection r when thecall isbeing made by anoperator. a 1 A stilliur'ther featureamay be, found in; the use of a paneljtype'selector 'iorseizing V V 1 the sender.

Otherffeatures are shown in the novel'cir cuit "arrangements which W111- be n1ore;;ep

parent from the fOllOWlIlg"ClQSCIIptlOHand o g g g g I I -'11}1]12L1S1I1 group 53 andthe othersettojmake appendedclaims.

, Reference may now 7 v p i panyingjdrawing' in which Fig. '1; shows ithe circuit ofalineswitch individualj to a sub scribers lineand adiagrainniatic, representa-- ="tion'of a second-line swit chindividual to In Fig. 2'18 shown the {circuit of a dis therefor; Y Fig. 3sho'ws oneof theregisterswitches.

g In Fig.5, the remai "ingregisterswitches H V jere shown, and-there are indicated diagram- It'jis' the objectfoff thisiinvention, to jlproide a link circuit which will be commonly selectors vision of means to difierentiate in; the sender canoellin'g the -selection of "talking battery be made :tothe a ccoin- T a" trunk extending to an operat ons position.

trict selector switch its associated sender selector 7 and 'a controll ng sequence switch I thec1ass circuit-,1 its contro1-{ ling sequence swltch aHd- V EL Il'OlIS"allXllllly inatieally portions of a translator; jointcontrolj which is positioned under the ofthe firstfltwc registers.

t {Fig 6: shows, thelsenderf -sequence switch together with yarious re- 7 In thisfigure are shown, withiuthe" dotted-section, cont-acts controlled rby' the lays;

class sequence switch of Fig; 3.

.and numerals on adial suitable foruse'with plication;

in which the Various sheets should be placed 1Fig-.;7ishowsjan arrangement ofi'letters V lcircuit' includ' ing the counting relays and: a:c tr 11 v a F 8 shows the relation tooneia'nother Fig. 9131mm a schematicarrangement of: 7

tion.

The former hunts over the terminals in "terminals inigroups 5,3; an d55'.i Each sender only 3 tjern1inals5 it 'is necessary to use two is arranged t0v makecontact With three tercontact with three terminals in group 55.

It -was not thought necessary myshow this ari-ange1nnt ingthe-kclrcuit diagram on F1g.-

Theisix terminals have been shown-in a one line forthe sake offsiinplicity. g o It will first be assumed that callgis]. iniitia tedby the subscriber at substation" 1.

Each district circuit is equipped withtwoi elevators, oneto make tliei uusal diStIlCtISB-f. lections and the otherf to select an 'idle sender; In the drawing, '51' is a district ele- 1; 1vator'land-52' asender selector elevator.

has six terminals and, since the district eleyator brushes are arranged: for contact 'Wlllll v 7 brushsetsforthesender'selector. One set I trunk terminal grouping whenjpanel type v are used for: mak ng s ender selec -1; f

Q 1- groups 54, whilethe .latter is confined' 'to i 1 195 7 iv-hen the subscriberlat substation l' re-- moves his receiver fronrthe switchhook, "a

circuit is"co1np1eted from grounded battery,

through the windingot line relay 2, inner lower arinaturefandback contact of cut-ofl.

10c I relay 3,rthrough the loop ofthecallingsuo' station line, upper' armature and back 0011- v tact of relay] 3 itoigi oundi Line relay 2 is fenergizedin this} circuit and attracts its armatures. Smcefthetest brushx5 lS'lIl en-s the energization line relay 2 completes} circuit from grounded battery, winding, armature and back contact of stepping magnet 4;, lower armature and back contact of cut-off relay 3, left hand armature and front contact of line relay 2, conductor 15, test brush 5, normal terminal to ground. Magnet 4 is energized and upon energization interrupts its own circuit to release its armature and advance the line switch into its first off-normal position. As soon as the line switch makes its first step off normal, contact 13 closes and ofi-normal spring 1 1 releases and engages its lower contact. Offnormal contact 1% removes the control of the cutoff relay from any line which may be calling and supplies its battery to test terminal 16 to render the calling line busy to other calling subscribers. The testtermin'als of trunks extending to busy district circuits will be characterized by the presence of ground potential on such test terminals as will be evident from the following description. As long as test brush 5 engages contacts of busy trunks, ground will be sup- .plied over conductor 106 to conductor 15 and stepping magnet 4 will continue to interrupt its own circuit causing the advance of the line switch. As soon as test brush 5 engages a terminal on which there is no ground potential the circuit of magnet 4 is opened. Then the switch 1s brought to rest with its brushes on the terminal set of an idle trunk leading to an available district selector.

It should be noted that during the operation of this switch a circuit is in existence for cut-off relay 3 extending from ground, upper and lower windings of cut-o1f relay 3, right winding of line relay 2, right armature and front contact of relay 2, left armature and front contact of relay 2, to grounded battery, through the winding of magnet 1. Cut-01f relay 8, however, cannot be energized in this circuit sinceits winding is short circuit-ed by the direct ground supplied to conductor 15 by means of test terminals 9. As soon as the brush set comes to rest on the selected terminals a circuit is completed from grounded battery, resistance 199, contacts of sequence switch spring 198, outer armature and back contact of relay 102, conductor 106, terminal 9, brush 5, conductor 15, right winding and armature and front contact of relay 2, windings of cut-off relay 3 to ground. The presence of battery potential on terminal 9 short circuits magnet 1 and allows cutoff relay 3 to operate. The operation of cut-off relay 3 causes the deenergization of line relay A circuit is then completed from grounded battery winding of relay 102, armature and back contact of relay 139, lower right contact of sequence switch spring 1053, conduct-or 10 1, terminal 11, brush 7,.lower mic 'd-le armature and front contact. of relay 3,

lower winding of relay 3 to ground. Relay 102 is energized and at its outer armature and front contact supplies ground to test conductor 106 and its associated contacts to render this trunk non-selectable to other hunting line switches. The energization of relay 102 also completes a circuit from grounded battery, left winding; of relay 107, upper contact of sequence switch spring 108, lower right and upper left contacts of sequence switch spring 109, inner armature and front contact of relay 102 to ground. Relay 107 energizes in this circuit. A locking circuit for this relay extends from grounded battery, right winding, inner armature and front contact of relay 107, conductors 110 and 111, lower right contact of sequence switch spring 112, lower right. contact of sequence switch spring 113, conductors 111 and 181, commutator segment 1S2, brush 183 in its normal position to ground. Lelay107 also completes a circuit from grormded battery, power. magnet of sequence switch 100, upper left contact of sequence switch spring 116, left armature and front contact of relay 107 and lower contact of sequence switch spring 117 to ground for moving this sequence switch out of position 1 and into position 2 under control of its master spring contact 101.

In posi-tion'2 of sequence switch 100, a circuit is completed for selecting an idle sender. A circuit for sender selector updrive magnet 118 is completed from grounded battery, winding of magnet 11S, lower left contact of sequence switch spring 120, left armature and front contact of relay 107 and the lower contact of sequence switch spring 117 to ground. The energization of magnet 118 causes the upward movement of the sets of sender selector brushes over the terminals in groups 53 and As soon as the commutator brush 183 leaves segment 182 the holding circuit for relay 107 is transferred from ground on brush 183 to ground on the terminals of busy senders. ll'hen an idle sender is found the absence of ground on the test terniii'ial of said sender breaks the locking circuit of relay 107. This relay deenergizes, opening the circuit of updrive magnet 118 and bringing the sender select-or brush sets to rest on the terminals of the idle sender. Relay 107 upon deenergizing, also completes a circuit from grounded battery power magnet of sequence switch 100, lower left contact of sequence switch spring 116, left armature and back contact of relay 107, lower contact of sequence switch spring 117 to ground for moving its quence switch out of. position 2 into position 3.

During the hunting movement of the sender selector a circuit exists from grounded battery, windings of updrive magnet 118 and relay 121, left contacts of se- Zque'n'ee sititch 122, r 'c ondnctori 105,

[outer left armatureend' front contact of re- 7 'fsetursuch a position as to control brush and group selections ettlie distru lziy 102 :to ground. The presence of direct ground at sequence switch spring 120 shunts releyij1-21'atthis t me to preventits operation. As soon as 'relay 107 is deenergized however, this shunt is removed and relay.

121energizes to corinectthe controlling leads in m1. associated with test brush 115 to; render to theselectedsenderfi Beliiy 121 at its inner left arinzituresupplies ground to the termithe sender non-selecteblefhy other selectors.-

soon as the sender has been seized and relay 121 has operated, a circuit is completed iron'if grounded battery, inding of relay 202,1loWerf 'ightand upper left contacts; of

sequence switch spring 203, conductors 204 V end 205, teStYbrUslr 115 :niid itsiissociated. 1 Contact, mane-t nne, inner {left armature and c hem; "contact jot relay- 121, to'fground; Relay, 202 is energizechin this circuit, and;

series of impuls i -com eletesfa circuit "from grounded battery,

"upper right contact of sequence switch spring 219, inner right; armature va'i'id front contactoi' relay 202 to ground, moving this sequence switch out of position '1 inte position '3 under control oi,- it'slj niaster sequence.

Winding of" sequence switch nie net .200,

switch spring 2 01.: I

The primary circu tof theinduction CO1l by'ineans 'ofjwhich the dialing tone is sup- I plied to the.callingsu oscriber extends from a suitable source-of tone" through the'left hand wincli'ngrof relay 213, conductor 21 1, register brush 500- in its .normalposition,

conductor 501, outer right sirinzit-u're fa'nd' f'backicon'tact of'reley 5'02, togroundst the, right-armature and back contact" of slo'W-tor' release relay 503. Gurrentin thiscircnit is" induced into the receiver vof the calling -snh-. scribers substation set "over a circuit extendingfrom grounded battery, Winding of t line relay 215, conductor 216,";sender selector brush 123f'enditsiessocleted contact, outer lefternieture and frontconta'ct of relay 121,"

conductor 124 lower left contact of sequence switch spring 125,1coziduotorf126, through,

thecontact of the line switch, to the ceiling subscribe'rs station, through the ,tip contacts of the line switclnconductor;127, upper left contact of sequence switch spring 128, conductor 129, sender selector brush 130 and its associated contacts, 091101110201, 131,: right armature and back contact? of relay 213,

7 middle Winding' of relay 213, conductor 298, progression switch brush 599, in its normal j position, to groundilVhen the calling sub,

sci'iber' hears this dialing ton'efhe operates his substation d al -32- to send out series 0t ini nilses to'the set of registers in the selcctedf sender. It ,Wiill be assumed thatthe line: to be selected I is one which terminates in a full mechanical; exchange which niey be selected directly by mem s oi? districtseai ,lector and an oiice' select-oi selection zit the final switch; 0

"switches the var? ztein n I 7 Inthisfcese'the registers nndcless 'eggisteis will here to he coming switches and brushi i Assuming that the .Wantedline Grand 561 8, in inspectionof the dial in Fig. 7 will show thet the su iscriber williirst insert his linger in the hole containing the" letter.{}

(1nd the'd gi 2 to se nd 4. impulses. sHe willfthen opei'zitehis dial tosend the 'lettcr Rf orS impulses after michvhef irill send series of t, 7, Send 9 impulses, respectively,

' V Inordert P i'event confusion as to which] i nsj brushes and contact v Figs, e encz'ne rcletechthe arcs shown I brushes belonging tosthe; progression switch or" side switch fliere; been indicated by the lctters i the armsbelongingf to theregister which isoperntedin responseto the first sends register are {identified jloy the letters Tin-and thoseof'the hundreds, tens and roup and line o'tfthe v ofli'ce code 1 have heen'designe'ted by tho letter- A,; the brushes belonging to the register which is operated in response to the secondseries of impulses,

shythe-lettenB';he brushes of the thou- ;I

units repisters have been designated by the letters 11, 1, and U5 respectively;

Retnrning to, theoperetion, relay 215 is I energized upon complet on of the above traced dial tone circuit and causes in turn theenerg'ization ofsloW-to-reieese relay 217 13 111611 intern ceusestheenergizationiof re c jieo M3 218. The" first interruption due tobthe operation of the; calling} sub'scribers dial causes the deenergizetlon oif'reley 215.

This iiiterrnptionrbeing of "shortdrirzition,

qhowever, reley 217 holds over, therebyinain fUpon the de: flenefrgizetioii of relay 215 a circuit iscoin- .1 b relay 218'energized.v

plated from grounded battery, throughl re- 4 sistenc'e 50 i, Winding-1 ofrelavy 503, conduca the register ;to advance one step Relay 503 is energized and being slow-to-release, m

Ilifilllsfilifgizetl untilthe completion of :1,

series of impulses; T In response touthe first series of impulsesv relay" 215 is deeii'ergized Etouirytunesend'jupon each deenergi'zation- 0811862 the stepping magnet 505 to advance {tlie'register brushes-one step," 1 Upon C0110- v pletion of the series of inipulsesthe A registier-(Will be in itsiourth off-normal position.

j At. thetermination of the series ofiinpulses, relay 7-215 maintains, its armamee ttre'ctedf'for eirelet vely long periodof time with the result that relay 503 is deenergized. Upon the deenergization of relay 502,, a circuit is closed from ground at the right armature and back contact of relay 503 to the winding of relay 519, conductor 509, upper left and lower right contacts of sequence switch spring 220, conductor 221, through the units register brush 512, through its normal contacts, and thence to brushes 513, 51 1, 515, 516 and the respective brushes of the tens, hundreds, thousands and B registers. resp ctii'ely, thence through brush 51?, or the .91 register which through the fact that this register has been posi tioned is in some oil-normal position, conductor 518, armature a d back contact of magnet 505, windings of magnet 505 and D 505, to battery. Relay 503 and magnet 005 not energized in series with relay 519. Relay 519 is energized in this circuit and completes a circuit from grounded battery, winding of side switch stepping magnet 520, conductor 521, eftt armature and back contact of relay 503, side switch brush and its normal contact. outer right armature and front contact of relay 51f, to ground. lilagnet 520 energized in this circuit and mores the side switch from its normal position to position 1.

it should be noted that the side switch which comprises brushes 507, 586, 581 and is preferably of the same mechanical construction as the register switches. The ore'ferred form of mechanism is similar to that shown and described in Patent No. 1,e"2,-165. issued to O. F. Forsberg and M. De Vignier on October 30, 1923.

T he calling subscriber now sends the sec-- ond series oi impulses in order to position the B register. The first interruption of the line circuit will cause the deenergization ot line relay 215, whereupon a circuit is completed from grounded battery, rc- "lance 501-, winding of slow-release relay 5U}, conductors 523 and 52%, winding of ppiug magnet 525, which controls the B register. conduct-or 526. side switch arm 507 which is in contact with its first oil-normal terminal, conductor 508, left armature and trout contact of re ay 212%, armature and contact of relay 215, to ground. Step- A p "-3 and relay are energized in this cir uit. Belay 503 being slow-torelease, retains its armature attracted until the completion or a series of impulses. Upon the next closure of the line circuit, line relay 215 attracts its armature and magnet releases to advance the B register one step. At the conclusion of the sending of the second series of impulses, the if; register will be in position 8.

At the conclusion of the series of impulses line relay 215 remains energized for a relatively long period. oi? time with the result that relay 503 becomes deenergized. he deenergization oi relay 503 completes a circuit from grounded battery, winding of side switch stepping magnet 520, armature and back contact of magnet 520, conductor 521, left armature and back contact of relay 503, side switch brush 522 in its first oil normal position, conductor 53?, brush 528 of the B register which is now in off-normal position, to ground. Magnet 520 is energized and interruvts its own circuit to cause the advance of the side switch into position 2.

In position 2 of the side switch the impulse circuit is diverted to stepping magnet 529 of the thousands register by way of the side switch brush 507 and its second contact, and conductor 530. Relay 503 and stepping magnet 529 are energized in series and relay 503 remains energized during the sending of the series of impulses while ste ing magnet 529 causes the advance of the thousands register into position 6.

Upon the completion of the sending of the thousands impulses, the side switch is advanced into position 3 over a circuit extending from grounded battery, winding of stepping magnet 520, armature and back contact 0t magnet 520, conductor 521, left armature and back contact of relay 503, side switch brush 522 and its second contact, thence by way of conductor 531 to the thousands register brush 532 which is now in oil-normal position, to ground. The side switch is advanced by means of this circuit to position 3.

The setting of the hundreds, tens and units register is accomplished in substan tially the manner described since stepping magnet 533, 53 1-, and 535 are successively brought under control of line relay 215 as the side switch arm 507 advances from position to position. Upon completing the settings of registers, the side switch arms will be in contact with the No. 0 oil normal terminals.

As soon as the A and B registers have been positioned at which time the side switch will be in posititon 2, a circuit is completed from grounded battery, winding of relay 502, side switch arm 580, and its associated contact, conductor 527, right armature and front contact of relay 218, to ground. Relay 502 is energized and completes a locking circuit for itself extending from its left armature and front contact, conductor 538, conductor 2T3, upper left contact of se quence switch spring 27 1, to ground.

The setting or" the translator switch will nowbe described. After being set into mo- 'tion, the translator will hunt for a position controlled by the joint setting of the A and B registers.

ilfliie constri,

on at the translator switch ilbsewss is fully. tlescfib'ed ili to' i Lumen, NO, 1,550,317, issued Ai1g.-l8,"1925.'

As soonias ielay 502 is energizedsci'rc'iiit .is completedyfroixi.;grcuhded hattery' 1resistf I ance 542, left; a rmatlireff'ancl lback Contact; Io'f ,relay 5428, ccncluctor "15 M,

I incling of power-magnet 540, v conductci 545 1nne1*' flight armature (andiront-contact of relay "aiiclts asscciatetl'iterminal;NOQS conductor .5 51,ithe N 131 contact in the are served'byj vh1 ush5 l6, conductors 552 ancl5 l5, togrou id,

-- register." l lish' h4g8. land i at the ai rmature and front contact of relay I enough magnetism toi a'llcw stc-pmagnet541 I 7 ,Of po'we magnet" 540, 1. grcunglat" thei air-c nmtureen dg front cg itactlcfrelay 502t The "502.? 'llhelcw resistance cf the right Winding Z 'f relay 543 shiintsthe power; magnet 540; and brings the tm risletcr switch; to" rest. 7 During the hunting" operation .cf this switch fla, circuit was in existencejor stop magnet 54f11f1'cm grcundecl battery, winding of mag, netJ 5 g0h1 .4 low; r i tan e r ht 2 Winding cf elay 54:3,Lleft'armetcreencljbeclg Contact of relay 5&3, cc diictelyfi, Winding current in thi's circuit fi's not lsu fiicie ritw tc energize inaghetzfi ll but 1t does .7 j-provlde togectjvery quickly when the proper" tere pr'opel terminal is; found staph magnet is energized fluete thecoiil jletioncf cin- 54:3; Magnet 1 5411s cwl} fully] energized and relay 543' is s ficientlyenergized to: at; tractits armzitjures, thu'sbreaking the drivi ndings in the :fWhcle' circuit.

,nding of power. niaghet vof sequence I sWi'tcl 1*200," lowerlleft ccntact ofqsequehce switch sprin 219," conductor 271 le'ft ar e n ajtmre sndfback contactfjc' fi relay 223; con- (luc tcr 227, inner itight'yai matlire and fi ontf contactpoi' relay 54:3, to-igro md folmming this jlsequence swl jchvqut oi" pcsitio n 3L j-filltl into a pcsiticn determined bythc setting .jot theftfanslatciiswitch, Sequence switch 200 dctel ri i esfthe class and routing of the cell; ancl n accordance/with 16$ s tting;

will determine" the iiihibeii and 'kiiid 'o'fii in large installation;

. 111g circuit '01": pcwcrmagnetlhg) z'ificlicgiusing V relay 7 543;? to include'ehotht its right and left s .handc,

J tche selit thzit is, hether cilie'e iinibulseslwhether. Whether 1 the call will be directeclto a; specielioperator or enyof th'e vm'iousrcombinations essential I The extent 10f motion'cf sequence switch] 200 willl'he 'cletermined by the point in its 1 Operation-ht which relay g228 gisfen'ei'gized'. i 2 e 7 Relay 223 has its circuit'successively extend; s 1

ed tc c0ncluct0rs 228, 229,230, 231,232,233, 23% 235 and- 236cm the sequence switch moves through its ,various"pcsitionsn These 2 conductors extend to arious terminals'inlthe I contact hanksgcfthe translator; I To aircicl I ccmplexity of the circuitsith ese leads have not been carrieddownftcthetranslator bank I terminals, 2: single conductor 553fbBlIIgl1tlized to indicate themanner in whichlthese 1 contacts willjbe connected to the arc of coii-ai 7 .'ta.cts;,which icontrolthe positioningecf zthe} Since ithas been coniplish'this, le 261* 229 would "hevewto be 700 reaches'ipositicnfi fi-a circuit isfconie pletecl from "grounded battery, w nding ,of

. v e t e I 85 assimied that'thecall'is' ftchi'e an; intercfficefull mechanical 1 call; the r class Qregister, thatis, se uence s'witch 200, r will be hi'cughtto'rest in p osi-ticnli #To ac- I Q0 "'wiledttcfthe N0i l3te1n1ina1i1i the classia 'c Q t .2 ot the contact bank served Ibyfthe brlisfh set ,L 0f the'1translator hensequencevswitchf relay 223; iippei left and lower right 0011 and lower, contact of sequence "switch 'spring tectsp-f sequence:switchspring'237,--conducv Itor1'229; conductor"553, ."N0.113.terinina15 v hmsh 554, I ccn d ictci 55 5; cuter rightarmafture an d front contact-ofxrelay 543, to

'cuhcl. lie-123 :2223 is energized and locks threugh its rightiarmature and front contact} 223 7 opens "the dr iving circuit t of 2 sequence H I switch 20D WhiCliliiingS this switch toiest chit fromjmagnet 541in;parallelgviththat v I ii just; traced for the Tight Winding; of relay? inpositibn 1 The energi'zatic j cf relay 223 alsc' com-H plet'es; a f "circuit from groundedi battery', power magnet Ofsequence switch 3QO,1ippeli left nccntact of sequence switch spring 813,? econductorslili and 15;:,leftv armature? and; front contact OilBlElYQQE), conductor 227', inner right armature and front Contact of relay 5&3tog1'0und forhicvingthissequence switch out o ffpositionl and intdpcsition 2. e i'i L S SOQR as sequehcesWitchf3OO reaches 7 ,positi011f2 afciicuit,v is ccmpleteclffrom grounded, battery, fight-winding o f relay.

1O'. left ccntects' 01 sequence switch springf H 1112, inner right armature andfrcnt contact-'1 V 0fielay121, senderselectcii hrush 132end itsjasscciated contact,,coi di ctoigl33, outer I right armeturemand back 'ccntact cfqrelay contact Qf sequence switchispring 24 0,

conductors "24:1 \and 316 inner right} ai'nia tureencl back contact of relays 317, lower 2 ight cci tict cfsequence switch springslty winding of stepplng relay 320, ainlaturee mull-hack contact at relay 321, Which isin;

switch 10.0,.lower Ileftcontact of? sequence 107 and when. brush 135' engages an insulat- The above inentionedenergization ofstep-H i ing segment of commutator 136 of the cir-J cult Q 1 relay lltfl isbrokenandthis relay. deene'rgizes completing a circuit 'frorn groundedbattery, powermagnet of sequence switch'spring 116,-left arn atnreand back 111g relays are broken 7 at, the upper I and" -lower iright contacts ofisequence switch;

i; In positionv of sequence iswitchfilOQ- a 5 fundamental circuit is againcompleted e.*;-v tending from grounded battery, right w1nd.

i we

energize;

- ture and front contact ofrelay 121'," brush contact of relay -1O7-,Alo,wer] contact of se; quenceswitch springf117,' toground,..inoring, sequence switch out of position into position 5.: The deenergization of relax 1107 also opens the circuitofupdrive ina'gnet'lifie and bringsthe {selector to rest in such pof I sition: that subsequent upward *niovenient will'cause the third setof'brushes to betrippedf As; soon-es sequence switchBOO' reaches 11 2, the locking circuits of thecount-fv spring ,325 i and; the countingi, relays deing-ofiline relaydOTg, left [contacts oifisequence; switch spring 112, inner 'rlghtnrnia- 1 32 "and ,its associated contact, conductor 133, outenright armature. andbackcontact" of relay239 contact of; sequence switch spring 240,1coridu'ctors 241 Sand 816, inner V "ri -ht armature. emitter contact of relay" i armature and: back: contact of" relay 321,; in nee-left armature; and back-contact of; re

layigoo,

31: 2 lower right contact,.,of sequence switch; "spr1ng318, wlnd ngof stepping magnet 320,

sistance 322i lower contact oi, sei quence, SWltCh spring 312; to, fground. rite laysg1.O7ja11da32OV are-energ zed n this C1I chit rela 107"coinnletin r a: lo'ckinw circuit 9 I 1' n m switch. lQOout of position fiafandinto p0 right andqupperfleft contactsof sequence released: into engagement "with "for itself through its right .Qarmature and frontwcontact', iconductors 110 and ill, and the contacts-of sequence switch spring 112; to. ground over'the path described. ;Reley 107 also'co1npletes a circuit from. grounded battery, power magnet-of sequence-{switch- 100,7,upperflcft' contact of sequence-switch spring" a 1-16, leftuarinatuie' and :front contact of: relay 1,07 lower co'n'tactof'sequenceswitch s urin 117; to round. for niovinv set uence sition 6.

-Inigpositioni 5of sequence switch. 100, i

.circuitjqwas completed, from *groundedhatteryywinding-cof trip magnet {137; lower:

In-position6 of sequence armature and back contact j of relto ground for? moving sequence switch 1-00 right and upper left Qcont a cts of, sequence ping relay 320 1 completes a circuit for the No. 3 countlng relayextending from ground) .ed batt'ery, winding of No; 3 counting. reQ

1ay, armatureand backcontact'ofthe No. s8"

counting relay, the No. l contect of the are served :by thrush 557,;conductor 560,:lowerflf contact of-sequence switchsprlng All, conn cw MductorAEZl, upper leit contact o sequence switch spring 323, lower. left c oinract of quence switchspringw; conductor Ste ner right" armature and back contact of re lay 306, 'onterv left armature and back? con ta t of relay 3O7 lower, contact offsequence switch spring 309, armature and front con- 1 tact of relayj 320, conductors j- 310 "and l 311 upper left contact of sequence switch: spring 312; to ground; The-'hlo. 3Ucountine' relay 1s energized and prep ares a circuit; ior the N0r3'count1ngrelay.

switch 100 it: cir- 'cuit is again, completedfor npdrive magnet 134:,frorh grounded ihatteryfwindin g 0f magnet 'l3,'l0 wercontact of sequence switch spring-; vleift armature and front" contact of relay 107 lower contectofsequence switch cspring l 17," to ground; The selector hr'n sh iand shaft w ll then-move upwardito, select the desiredrgroup; As soonas commutator brush 194 engages 'a conducting portion of commutator 138 stepping relayBQQ 'isl shuntv ed down and deenergi'zes' to allow theflen I ergizati'on 0i counti'ngfrelayNo;3;

On the fourth I shunting down ofstepp relay 320,- counting relayOi injqzxrallel with, I relay 821jis' energized as previously described. 'Theenerg-ization of countingf'relay O completes" a circuit from grounded battery, wlndlng or power ,magnetonsequence switch .SOOfupperfleft contact of sequence switch spring 331,;conductor 34.05 outer'armature and back contact of creley 332,1 inner'right arinatureand hack contact of relay- 307', to ground at the armature and; conta'c-tfof the 0' relay; Sequence switch 300' is" advanced out of-position '2 and into.

position 4. The energizationof relay. 32L

opens the lo wer branch of thelo'ckingcir cuit of the relay-107 and when, afnionient later, brush 194; engages an in'sulating seginentof coinn1ntato1' 138;the locking circuit] of; relay 107: is bi okenandthisrelaydee'ner- ,gizes. The deener ization of relay- 107 corn-r} pletes'a circuitfroin grounded batter'yyp'ow I er magnet of sequenceswitch 100, lower left; contact of sequenceeswitch sprino llxi jlei't lowercontact of'sefcuence switch; SJllDS- A .a

fiery, left winding o frelay-10finppercon;-

tact of 1 sequence switch: spring;- 108 lower quence switch spring 117, to ground.

' armature conductor switch spring 109, inner armature and front contact of relay 102, to ground. Belay 107 is energized in this circuit.

lVhen sequence switch 300 reached position 4:, circuit was completed from grounded battery, winding of relay 152, lower con-- tact of sequence switch spring 1 0, conductor 1e11, outer rightarmature and front contact of relay 121, left contact of sequence switch spring 1 1-2, sender selector brush 143, and its ssociated contact, conductor 1 514., outer left and back contact of relay 930, 24-2, resistance E2123, conductor 214-, upper contact of sequence switch spring 3-11, to ground for energizing relay 152-.

It is to be observed at this point hat when sequence switch 100 reached position 3, a circuitwas completed from grounded Jattery, right hand winding of relay 139, upper left contact of sequence switch spring HO, conductor 1 11, outer right armature nd front contact of relay 121, left contact of sequence switch spring sender selector brush 1 13 and its associated contact, conductor 1 14:, outer left armature and back contact of relay -30, conductor 21:2, resistance 2 13, conductor 21-1, upper coiract sequence switch spring 3 11, to ground. Relay 139 was energized in this circuit and at its left armature transferred the holding circuit of relay 102 from the lower right contact of sequence switch spring 103, to the upper-right contact of sequence switch spring 103. Relay 139 remains energizet until sequence switch 100 leaves position 10.

lVith relays 107 and 139 energized in position 7 of sequence switch 100, a circuitis completed from grounded battery, power magnet of sequence switch 100, upper left contact of sequence switch spring 116, left armature and front cont-act of relay 10?, upper contact of sequence switch spring 11?, right armature and front contact of relay 139, to ground for moving sequence switch 100 out of position 7 and into position 8. As soon as sequence switch 100 reaches position 7 a locking circuit for relay 107 is completed extending from grounded battery, right winding of relay 107, inner right armature and front contactof relay 107, conductor 110, lower left and upper right contacts of sequence switch spring 145, to test brush 141-6 and its associated contact, and thence to ground, providing the associates trunk is busy.

It will be assumed that the first trunk in the group is busy. Relay 107, therefore, remains energized and completes a circuit from grounded battery, winding of updrive magnet 18 1, lower contact of sequence switch spring 120, left armature and front contact of relay 107, lower contact of se- The selector brush set is now moved upwardly over the terminals in the selected group and when an idle trunl: is encountered ground will no longer be found on the terminal as sociated with test brush 116. This branch of the locking circuit of relay 107 is therefore hrol-tcn but the relay is held energized an i2 int longer in order to properly center the. brush set due to the closure of the circuit extending from grounded battery, left winding of relay 101', lower contact of sequence switch spring 108, a conducting portion of commutator 119, commutator brush 118, to groun 1. As soon as commutator brush 113:8 engage, an insulating segment of commutator 1 19 at which time the brushes will be accurately centered on the selected terminal set, all branches of the locking circuit of relay 107 are opened and this relay decnergizes, causing, in turn, the deenergization of updrire magnet 134 and bringing the selector to rest. The district selector has now been actuated to seize a trunk leading to an idle office selector switch. The deenergization of relay 107 also completes av circuit from grounded battery, powerniagnet of sequence s *itch 100, lower left contact of sequence switch spring 116, left armature 1 back contact of relay 107,1ower contact of sequence switch spring 117, to ground for moving this sequence switch out of position 8 and into position 9.

li ith sequence switch 100 in position 9, a circuit is in existence from grounded battery, left winding of relay 10?,upper contact of sequence switch spring 108, conductor 161, lower contacts of sequence switch spring 109, right armature and front Contact of relay 152 to ground for energizing relay 107. The enc' zation of relay 10? completes a circuit from grounded battery, winding of power magnet of sequence switch 100, upper left contact of sequence switch spring 110, left armature and front contact of relay 10?, lower contact of sequence switch spring 117 to ground, for moving this sequence switch out of position 9 and into position 10.

During brush and group selection and trunk hunting of the district switch, relay 210 is maintained energized over a circuit extending from grounded battery, winding of relay 210, conductor 2 15, lower right contact of sequence switch spring 342, outer left armature and back contact of relay 306, conductor 313, sender selector brush 150, and its associated contact, lower left and upper right contacts of sequence switch spring 151, to ground. The function of relay 210 is to prevent the advance of the sender controlling sequence switch until trunk hunting has been completed at the district switch.

As soon as sequence switch 100 leaves position 8, relay 210 is deenergized completing a circuit from grounded battery, power magnet of sequence switch 300, conductors and 33?, left armature and back contact of relay 210, conductor 338, lower contacts Toaccoinplish the selectioniof talking battery the sequence switch 100 is caused to rotate through various positions and while rotating sends revertive impulses into the sender circuit to control counting relays operated in accordance with the setting of sequence switch 200. This is accomplished inthe following manner.

Sequence switch 300. is in position 14 of its second revolution. A circuit iscoinplcted from, grounded battery, right winding of relay 107, left contacts of sequence switch spring 112,, inner right armature and front contact of relay121, sender selector brush 132and itsassociated contact, conductor 133, outer right armature and front contact of relay 239, conductor 267, lower leftv contact of sequence switch spring 318, winding of stepping relay. 320, armature and back contact of relay 321, inner left armature and front contact of relay 300, right contacts of sequence switch spring 3458-, resistance 322, conductor 869, lower contacts of sequence switchv spring 370,.outer right armature and front contact of relay 357,. conductor 371. side switch brush 581, and its associated 9th terminal, conductor 582, right armature and back. contact of relay'218, to ground. Relay 1.07 and stepping relay 320are energized inthis circuit, Relay 107 upon cnergization completes a circuit from grounded battery, power magnet of sequence-switch 100-, upper left contact of sequence switch spring 116, inner, left armature and front contact of relay 107,, lower contact of sequence switch spring 117, to-ground,.1noving this sequence switchout of positionll and intoa position to bedeterinincd by the counting relays. Relay 1,07; completes a loeking circuit for itself by way of its inner right armature and front contact, conductors 110 and 111, low -.r right and upper left contacts of sequence switch spring 112 to ground over the path described. The energization of stepping rolay. 320 completes a circuit from grounded battery, winding oftheNo.-.0 counting-relay, upper left hand contact of sequence switch spring 268, left armature and back contact ofrelay 213, conductor 2.99,.lower right and upper left contacts of sequence switch spring 363, conductor 394,-, inner right urinature and front contact of relay 306, outer left; armature and back. contact of rel ayv 307, upper contact of sequence switch spring300, armature and. front contact ofrelay 320, upper right contact ofsequence switch spring;312, to ground. The counting relay is energized in this circuit and prepares a. circuit for the O counting relay.

lVhensequence-switch 100 leaves position 11 a circuit is: momentarily closed from grounded battery, right winding of relay 107, inner right armature and front: contact of; relay 107, conductor 110, left contacts of sequence switch spring 1 15, to ground; Steplay 218 to ground.

1,ssc,sss

ping relay 320 is shunted down in this circuit and allows the 0 counting relay in parallel with relay 321 to be energized in a well known manner. Relay 321, upon energizing, opens the lower branch of the circuit of relay 107 and, when sequence switch 100 leaves position 11%, the upper branch of the holding circuit of relay 107 is broken and this relay dcenergizes, opening the driving circuit of sequence switch 100 and causing this sequence switch to come to rest when it reaches position 12.

Dur-ing'the selection of talking battery, the holding circuit of relay 121 is no longer controlled by the outer left armature and frontv contact of relay 102 since tl c sequence switch 100 has left position 11. Due to the energization ofv relay 107 a holding circuit, however, now extends by way of the upper right contact of sequence switch spring 1450, conductor lell, outer right hand armature and front contact of relay 121, lower right contact of sequence switch spring H2, outer right armature and front contact of relay 107-, conductor1i7,lowcr right and upper left contacts of sequence switch spring 1 315, to ground. When talking selection is complcted'and relay 107deenergizes as previously describechrelay 121 is deenergized and at its inner left armature removes ground from the terminal associa ed with test brush 115 so that the sender is now selectable by on sender selectors. The removal of rrounil from test conductor 205 allows relay 202 to become deenergized. A circuit is then completed from grounded battery. winding armature and' back contact of side switch stepping magnet 520, conductor 521, left contact of relay 508 side switch brush and its associated 9th terminal, condu 583, outer right armature and back con of relay 202,,to'ground. Magnet 520 is energized'in this circuit and advances thesidc switch into its th position. A circuit is then completed from grounded hattery, winding of the power magnet of i. switch 200, lower left Contact of sequel. switch spring 219, conductor 270, side switch brush 581 and its 10th contact, conductor 582,, right armature and back contactv of re- The completion of this circuit inoves sequence switch 200 out of position 7 and into position 10. llhen sc: quence switch 200 leaves position 15 relays 239, 263 and 259 are deenergized. in. potion'16 the operated winding of relay 5052 is shunted down due tothe closure of the circuit frorn grounded battery, resistance conductor 5845, lower left and upper right contactsof sequence switch sp ing 220, conductors 271 and 270, side switch brush 581 and its associated contact, conductor right armature and back contact of relay 218, to ground. Relay 502 is deenergized causing-the deenergizatio-n of relay As new r 3 scenes relay502 fis deenergizedia circuit-is completed "from grounded batteryp. power j magnet-of sequence sw1tch32O0, lower right i ccntact'of sequence switch spring 219, con:

- ducto-r 272,1eft fir-meme to back contact of -relay 502, conductorsl538 and 273, upper contact of sequencefswitch SPIlHQ" 274, to

It should be noted-that the locking c rcuit deenergization of. relay 306 causes in; turn the deenergization of; relays 3l7fi and 357. I

' The ,deenergization of relay543 completes a circuit fromigrounded battery, power magnet of'sequence switch;-130O,]lower right contact of sequence 7 switch spring 313,, coi1ductor j 376,1 outer right armature and backcontact of relay '543,;to;ground'for moyingtsequence out f ofposition 1'4 and into po sition l, c e In position l7 of-sequence switch 200 with theside switchiof Fig; i4:, in position 10, cir-v cuits are-completedffor restoring the regis ters. The unitsregister-is the first to be re-' stored in ,a circuit extending from grounded battery, resistance 504,,iwinding of slow to release'relay 503tconductors523 and 524,

winding of; units register stepping magnet 535," armatureand backcontactof magnet-J1 -535, ;register brush 512;;and itjsroff-normal 7 'contact,'conductor 221,; right contacts of senormal position. H i 1, 4 I iThetens register is nextto beres tored. 1A 4 self interruptingcircuit for its stepping mag g;

net is completed from grounded batteryfre-f .sis tance,50 4,1 winding of 'slow-to releasire lay 503, conductors 1523 and 524,- winding of; v tens registerstepping magnet 534, tens regisf ter brushi 5lf3gand its off'zsnormal*contact;

quence switchspring 2 20, conductors'27 land 270,side'switch brush 58l and its'associated contact, conductor ,f582,'right armatureand 5 back contactof re1ay 2l8tto groundgi Relay V 508 and magnet 535 are energized}; Magnet 535, interrupts its own circuit until the units register has advanced into its normal; position at which time,no further. circu t being found 7 for, magnet; 535,;jthis magnet f remains deenergized with the units "register its thence through 5 units registerbrush 512'an'd vfurtherdescription.

its normal; contact to conductor 4,221, to

controlsj ofr magnet 534 the tenfsxregisteris which it is thought will The translator switch does not haye a .nor-

mal position but remains in the position to tion. a k

; I Asfsoon asthe registers are completely're} 5stored,,a circuit is (completed fro'mgrounded I v I battery, winolingiof side switch L stepping In'a'gnetlf520, armature and back cont a,ct or} magnet 520, conductor52leleft-armaturefand1 Y 7 10..

back contact of relay 503, Side switch brush 522 and its jl'Oth' ofi-normal contact, conducand units registers respectively, in series, to conductor 221, then toiground over the path previously deseribedi r This circuit energizes magnet 520 wh ch advanced-the side switch into position 11" from fwhencejitj is. driven to itsnormal position in a self-interrupting cir cuit leadinggthrough brush 581', to ground, at the rightarmatureand'backcontactiiof e relay 218. The registers and theircontrolling; e 5-,- I,

side switch have now allfibeen restort-zd-v to theirinormal"positions. ii A ci rcuitis now completed battery, power gmagnetj of sequence switch tor 585,; A registerbrush 517 andeit-snormal J Contact,irand thence through brushes 516, f e- 5175, .14, 513,-fand 5l2 and thenormal' con w tacts of the B, thousands, hundreds, tens,

from grounded 200,1 upper; left; contact of sequence switch 1 spring 219, c on'ductori 275, side switch brush 581 and-Qits'normal' contact, conductor 582,

right. armature and back contact of relay 3 e218,'togroufnd.u' The completion ofthiscirtion 17 and into' position 1. e- 1 "cuit, moves sequence switch 200/out "of posi-Q "ratus' arenow in theirnormalcondition and are ready tor reuse upon seizure-by other districts. A te the incoming selector appliesrin l .e

ing :current and,the called subscriber an- 1 swers, fpolarized' relay was: energized .over afcircuitextending into the incoming lselectorg -fThe energization. of relay 160 completcs] a j v circuit from 7 grounded e battery, I .Windingof charge relay l52,"-rightfcontactsof sequence. switch spring .109, conductor 164, armature and'front contact ,of relay "1 60, Contact of sequence switch, spring 166, :1 to-ground. Relay 1'52, isenergi'zed'in this circuit and locks'up through the upper left f j and: lower rightcontacts oi sequence switch {leaves position 18, H k

- The 'connectionis nowcomp'leted .anclkthe" I '5 subscrlbers may converse." The talking con- .1- ground {over the path described. 1 'Under the? .ductors of the. calling subscribefls lin'e'dare spring 109 and'its' right armature and front contact to. ground,;untilsequence switchlOQ i mainso connectedinposition12 of sequence,

is included and energized inthis circuit. Relay 139 isa' diflerentialIy wound relay switch 100; 7 Battery issuppliedto-the calle ing subscribefsline through' the"windings I ofthe repeatingcoil. Supervisory relay 167*,

to 11 of" sequence switch 100 by a circuit from grounded battery, left hand" winding of relay 139, upper right contact of sequence switch spring 1-22, to ground. Inpositions 1 to 10 ot'sequence switch 100; a circuit is in existence through the right winding of relay 139; but since this circuit includes the resistance 243 in Fig. 3, the magnetism setup inthe right winding of relay 139' is not sutiicicnt to overcome the polarity of that set up in the left windingand therefore relay 139 remains energised; hen sequence switch 100 reachesposition- 10 the supervisory relay 167 is ener 'ized and" the holding-circuit of relay 139 now extends throughitsleft winding, armature andifrontcontact of" relay 1'67, and the right armature and front contact of relay 1 89, to ground hensequence switch 100 reachesposition 11 the circuit of the left winding of relay 139 is entirely dependent on the relay 167.

hen the conversation is completed and connection is no longer desired, the calling subscriberreplaces his receiver. Relay 16? deenergizes and causes in turn the. deenergization of" relay 18i A circuit is thereupon completed from grounded battery power magnet of'sequence switch" 160, conductor 1'68; upper right and lower left contacts of sequence switch spring 169, right arn'iature and back contact oi re lay 1'39 to ground, moving sequence switch 100 out of position 1 2 into position 18.

its sequence switch 100 reaches position 17 a circuit is completed from grounded batter-y, winding otsender selector downdrive magnet 18a armature and back contact of relay. 185, lower contact of sequence switch spring 186' to ground; The sender selector brush shaft is returned to its normal position by mag-net 18a. As soon as brush 183 makes cont-act with segment 1-82 on the downward movement of the brush shaft a circuit is completed fron'r grounded battery, windingot relay 185-, right contacts of sequence switch spring 198 conductor 187 commutator segment 1182, brush 1 83 to groundi Relay 185 energizes in this circuit breakingthe circuit of downdrive magnet 181 and bringing the sender selector brush shaft to rest in its normal position.

In position 18- of sequence switch 100 a circuit is completed" :tron'r grounded battery, winding otdowndrivemagnet 178; conductor 191 contact of sequence switch spring armature and back contact of relay 188 to ground. The district brush shaft is returned toits normal position by magnet 178. 1&3 soon as brush 148n1altescontact with the commutator segment 179 during the downward motion'of the district brush shaft, a circuit iscompleted from grounded battery, winding of relay 1538, contact of se quence switch spring 189, conductor 190.

commutator segment 179* brush 148 to ground Relay 188- is energized in this circuit. It upon the return oi the district shaft the sender selector shaft has also been returned to normal, brush-180 is in contact with con'nnutator segment 19? and a circuit is completed from groundedbattery winning or" power magnet of sequence switch 100, lower right contact of sequence switch spring 116, conductor 1%, commutator scg ment' 191', brush 180, conductor 195 armature and "front contact of relay 18-8 to ground, for moving sequence switch lOO'out of position 18- and into position 1. It, however thedistrict brush shat-t returns to-normal before the sender selector brush shaft, the sequence switch 100 will remain in position'18 until the return ofthe sender selector to normal.

As soon as the sequences-witch 10(i'leaves position 17 the battery suppliedon' the sleeve terminal of the line switch is cut-off and the cut-oil'- relay of the called line is deenergized, allowing the callingsubscribers line s itch to be restored toits normal position; The deenergization of relay 102 also removes tliebusy ground. condition from the test terminal of the line switch to render the district switch selectahle'by other hunting: linc switches;

.he release of the calling subscribcrs individual line switch tal-tes place'as follows: As soon as sequence switch 100 leaves position 17, battery is no longer supplied to conductor 10% and cut-oi'i relay is deenergizedl A circuit completed from grounded battery, winding, armature and back contact of stepping magnet 4-, lower most armature and back contact of cut-oft relay 8, left arn'iature and back contact of line relay 2-, oft-normalcontact 13', to ground. Magnet at is energized in this circuit and interrupts its circuit to cause the advanceof the line switch. Magnet 1 continues to interrupt its owncircuit to advance the line switch into its normal position. iVhen the line switch reaches its normal position, of?- normal contact 13 is opened and the line switch is broughtto rest in readincss for reoperation.

This completes the description of a call initiated by a calling subscriber. However, it is sometimes necessary that an operator complete a call for a calling subscriber who finds diiiiculty in dialing. lVhen such occasion arises, the operator must have access to the same appa atusasthe subscriber would ordinarily have. Therefore, when the operator receives a signal from the calling subscriber whose line terminates at her position, she inserts the plug- 35' into jack 36, Fig. 1 A circuit is closed from grounded battery, winding of relays 37 and 3st. sleeve contacts of plug 35 and jack 36 to groundi j The eiiergization of -i relayl34e causesthe illnmination of supervisory lam 38 and the energization of; relay .371prepares a circuit V for relay-=33 which is' completed iponythei closur'e the tip and 'ring'ofthe cord. i circuit" ei t'tends froin-i'gronndedf""batteryi through the' lleft windingjoflrelay 33, left armature and front Contact of relayi37, up; per Winding of; V repeating "coil 29 ti .-.con1- tacts-of plug- 35mm jack 36 through the" 1100p of the 1' sub'scr'ibers station,- ringg'con tacts of jack and plug 35, lower inding of repeating -coilf29 right armatnre and' front contactof relay '37,}rifght windingiof relay 33 .to "ground The energization of re-Y lay 33in this circuit places;a*- shunt circuit around'danip I385 extinguishing it" and also -supplies talking'battery to the. wi lingl -line:

Upon ascert'aining the number desired by! theca-Hing subscriber, 'the' operatorinserts plug 23f intoj'ack 21 atfh'er position and ope'rates'dialiiigkey 25f;A circuit is then I completed for 'pemtingf'the line relayiin linfeY'switchAO. isms described above for a i station- -to station call. "Since thesame' type of apparatuses usediiiie switch-1,40 as inthe subscriberis lineiswitch the saine desige. nations will be: need for both: "fThe operation selecting the'districtfis *then the same as that 'described- -iii relation ito a calling sulbfl .sc 'iber. After thelsender has been selected 5 111 1116 "manner dGSOIlbGd-dlilhflg toneis given 34v its associated contact 0fthe line fs'witch,g

to'the operat'ori The operatorthen proceeds tqigmanipulate herl dia' l to: se'nd' out' series of. impulses; A 'circuitfisf in existence from grounded battery; resistance 27 10wer contact of dial; 26]," upper contact of dialing keyf',

I 1 conductorilQ'F, upper left 'contact'oi sequence v switchfspring j128'; condnciton 129jsender selector bri'ish 130 and. its associated contact, .1

conductor 131, right arniat uTe fand back:

contact of relay 213, high. resistance inter mediate Winding of 're1ay21 35 condiictor 298, brush 599 ef-"the *side switch and, its las first operation of thefdia1',;re1ay 52,13 finerwindin of rela 1:.213' j-ri ht armaturefland i b y 7 b f front contact of relay 213, intermediate Winding of relay 21 3-,t0g'rm1nd, over the path described. The energization of relay 213 'i-sthe signaIfi-to thefsende1f that an" operator and-janota subscriberj 'is' dialing sin cerelay '2l3,"as:fw i'l1; be rernemberedfwas I not energized over the subscribersfidine; This was diie to the factfthat pulsing relay 215 was inch d'ed in theicircnitiof relay 213 and there was, ins'uflicientfcurrent flowing in theQci'rcnit. The circuit for. pulSinQnowexQ tendsfroni T grounded battery, 'W'indingof remy 215 condiictor 2l6; sender selector brush sociated norinal contafct to ground; Orfthe' ouit for itself-by Way ofiitsinner'right ar-' armatureand front contactof re1ay"121', con- 3 123 andits!assbiatdifbiititifinder f leftf dil'c'torl l2L,;loWer* left Contact of sequence scribed it: a i ailing siibscriber until. I the selection oftalking battery; It willbe noted" is restoredfj to its 3 normal position; w 'As is;we11-known-, whenanoperatororigifj f c inates a calhat-alkingbatteryiis s ippliedfrom; V the'operatofsjset so that} fit isinecessaryfin 'inalgingf'talking selection thati the district repeatingcoil becut outof the circuit. This a is accomplished because of the 'energi zationif of relay 2l31iabov edescribed. 1 As will be rementers 1 inlthe 5 description; of the selec 'tio'n ,ofj tall zing battery for a snbscribers call;sequence swit'ch was caused to rotate, V .1

,iimpnlsesitothesendertcirciiit andlcont-rolling through I various: positions,' sending revertive herethlat upoirthecompletiongofdialinghey; 7

counting relays" operated in "accordance with l the setting of sequence switch T200.fWit1i sequence "switch 30 0fin position 14: of its,

second revolution, a OiICiilit is completed from} grounded battery, right Winding of relay I07," leftr contacts: ofisequence switch spring-112; inner right-armature and front c0ntact of relay 121, sender"selector brnsh' 132iandits, associated contact, condnctor 133;Outer right armature and front contact of vrelay, -239,

conductor 267, lower left contact of sequence I switch spring 318, Winding of stepping relay o 1 820, armature and back contactof relay 321, j inner left armature and'frontcontact'of re- 1 lay 306, right contacts of sequence, switchf C spring 34$,yresistai1ce" 3225' conductor i369; I lower :cont-akztslof sequenceswitch spring 370,

outer ri -ht armature and front, contact of relay: 35?,- conductor1371; side s itchbrush '581' and its associated 9thv terminaL- conductor 582; right "armature and back contact ojf I relay 218 to ground. ,gR'elay,IOTandijstepf circuit from grounded battery, power'imaglower contact of {sequence ,fswitch spring 1 l7 to ground, -for moving this sequence 'f'ping-relay 320. are energized in this circuit. i

Relay 107,npon energizat on, completes 3:1 .51

switch. out ofgposition 1 1' andfintoa po .sfition to- Ib'ef determined 'by;' the counting ff relays; Relay 10 7 completes a locking (zi mature and front contact, J :condiictors 1 10 spring 112, to; groiin dnover the path described. The energization'of stepping-relay and 111, and the contacts of sequence switch 

